I would strongly suggest that you increase your water intake (purified, not tap)to half your body weight in ounces. 1/8t Sea Salt (not table)for each liter of water.
My thyroid felt tight and swollen for awhile when I first started supplementing Iodine (10mo ago). Then I was taking it only once a day (50mg) in the morning, but when I upped my dosage to 100mg (not mcg)and spread them throughout the day, the tight/swollen feeling went away. Some feel as you give the thyroid what it needs it seems to awaken the thyroid and stimulates it, and spacing keeps the amount more consistant. If I take my last dose in the evening my throat (thyroid) doesn't seem to bother me, anymore.
Everyone is different in how they respond to Iodine supplentation, but virtually everyone is toxic and it takes a significant amount of Iodine to displace other halidides out so iodine can get to the places it needs to be.